Trailer Dolly Apparatus

ABSTRACT

A load-bearing trailer dolly which connects a tongue-type boat, utility or other trailer to a towing tandem trailer and bears weight from the trailer during towing. In a preferred embodiment, the trailer dolly is characterized by an axle mounted on a pair of wheels. A dolly frame height-adjustable trailer hitch centered coaxial above the axle axis and midway point framed dolly plate mount by operation of an adjustable sleeve reducer fastened by pinning and lock. Includes dual connecting adjustable height tongues for attachment to rear end trailer hitches on the tandem towing trailer at which a pair of hitch fasteners for engaging the trailer dolly tongues are attached to the rear of the tandem trailer. The adjustable tongue hitches on trailer dolly will give ability to horizontal level tandem dolly. A shock-absorbing spring is fitted between the axle mount and the dolly frame for cushioning the dolly frame on the axle mount as the trailer is towed behind the towing tandem trailer. In the industry of dollies, the car dolly has no shock-absorbing function, just square axle with hubs for wheels, axle is attached to car dolly frame. There is an option with shock-absorbing mechanism or s non shock-absorbing option.

CROSS-REFERENCE TO RELATED APPLICATIONS

U.S. Pat. No. 3,865,405A/1975 inventors Stanley W. Mitchell and Edward N. Spenchuk, U.S. Pat. No. 2,592,219A/1952 inventors Leonard R West and Overby B Sterett, U.S. Pat. No. 6,681,535B1/2004 inventor Ty Batchelor, U.S. Pat. No. 6,685,211B2/2004 inventor Arthur R. Iles, U.S. Pat. No. 2,450,215A/1948 Inventor William A Wilson, U.S. Pat. No. 6,820,887B1/2004 Inventor Robert E. Riggle, and U.S. Pat. No. 3,421,777A/1969 Inventors Stephen Barker, Paul F Bennett.

FIELD OF THE INVENTION

The instant invention may be considered in the field of tandem-trailers trucked triple, can be exceptionally long consisting of a truck or SUV pulling two trailers hooked up tandem. Where a trailer dolly apparatus is used to support the weight of the last trailer that attaches to the other tandem trailer supporting the weight on the dolly not the tandem trailers rear end hitches. Not exceeding light tongue ball and hitch to truck or SUV will cause a more harmonious outcome.

BACKGROUND OF INVENTION

There is a need in the industry of trailer dollies. Larger trailers, typically fifth wheels, are heavy and can attach another trailer in tandem in a triple configuration of two trailers and a towing vehicle. The lighter ball-mount hitch trailer should not try to haul in tandem unless the second tail trailer is small and light.

Trailer dollies are patented for supporting the tongue-weight of a trailer while being towed. The connecting means of the towed trailer is behind the towing vehicle not designed for triple towing (U.S. Pat. No. 3,865,405A/1975 Mitchell et al., U.S. Pat. No. 2,592,219A/1952 West et al., U.S. Pat. No. 6,681,535B1/2004 Ty Batchelor, U.S. Pat. No. 6,685,211 B2/2004 Inventor Arthur R. Iles, U.S. Pat. No. 2,450,215A/1948 Inventor William A Wilson, and U.S. Pat. No. 6,820,887B1/2004 Inventor Robert E. Riggle).

A dolly for semitrailers has been patented. This transportation dolly is mainly used to improve the connection of two semitrailers in tandem. This type of apparatus assists in distributing the tongue weight of the last semitrailer onto the support dolly not applying forces to the other tandem semitrailer (U.S. Pat. No. 3,421,777A/1969 Inventor Barker et al.).

Situations, where the trailer reaches its gross trailer weight is when the weight of a trailer is fully loaded at maximum capacity. This condition causes increase trailer tongue weight that can weigh as much as 3,000 pounds. Tongue weights of this magnitude can unsafely overload the weight capacity of the camper trailers rear end when traveling. An increased load as much as 3,000 pounds, for example, a tandem trailer tongue hitch without dolly attached at rear end of the travel trailer frame will have problems traveling through bumps, potholes, bridges, and similar occurrences during travel which can damage the frame, chassis, and/or body of the trail trailer. An unsafe condition for the towing vehicle.

Other issues happen when the tandem trailer is towed in a position that is not horizontal with respect to the road. This produces unsafe forces on the tandem trailer tongue and hitch during towing that is not designed to safely support under tow.

Accordingly, what is needed is a dolly for towing tandem trailers that overcomes the frame, chassis, and/or body damage to towed trailers, the horizontal alignment of the trailer, and the steering drawbacks of conventional modes of towing dual trailers being two trailers and a vehicle.

The proposed patent application differs in that the trailer dolly is used primarily behind the travel trailer in a tandem triple towing configuration and is used to support the tongue weight of the last trailer. This tandem towing can be accomplished without a commercial driver's license (CDL) or class A license.

SUMMARY OF THE INVENTION

Regarding triple towing, fifth wheel trailers come with a tow hitch sleeve at rear of the trailer for towing tandem trailers. The problem is some fifth wheeler trailers are too long to legally tow tandem trailers. Trailers are allowed up to 45 feet maximum length. Fifth wheels trailers range from 25-45 feet. Maximum length of the towing vehicle and trailers combined is 65 feet with a basic class C license. Maximum length of the towing vehicle and trailers combined is 75 feet with a commercial class A license. With a 45 feet fifth wheel trailer towed by a typical class C license truck range 17-20 feet in length, the maximum legal length of 65 feet approximately happens with not option for tandem towing with a basic class C license, and with a class A license the recreational trailers can be no more then 10-13 feet in length.

The average travel trailer or a camper trailer are around 20 feet in length and 8 feet in width. Travel trailers need a towing truck or a SUV depending on the size and weight of the trailer. This type of trailer is generally tongue and ball hitch attachment. These type of camper trailers do not come with a towing sleeve attachment mounted at the rear of the trailer for tandem or triple towing due to up lift. This inventions niche in the market hovers within these average camper trailers. A 20 feet truck or SUV attached to a 20 feet camper trailer can haul 25 feet more in tandem triple towing and be within the maximum limits for basic class C drivers. The trailer dolly subtracts about 2 feet from the 25 feet giving the vacationer a total of 23 feet for a recreation vehicle (RV) trailer. The problem with a 23 feet boat and trailer can be heavy at the tongue hitch causing sway of the camper trailer tongue hitch.

Many vacationers tow triple tandem trailers with fifth wheel trailers that are heavy most ranging 7,000-20,000 pounds depending on the trailer length. Towing in triple with an additional tandem RV trailer is no problem for this type of trailer. Camper trailers with ball-mounted hitch weights range between 1,550 pounds for a 13 feet trailer to 6,600 pounds for a 35 feet camper trailer.

Trailers with ball-mounted hitches should have tongue weight that is between 10-15% of the total trailer weight. Example, a 3,000-pound ball-mounted hitch trailer is loaded with 2,000 pounds of cargo, the proper tongue weight of the loaded trailer should be between 500 and 750 pounds.

When the tongue of the trailer does not have enough downward weight on the towing vehicle's ball mount hitch, the trailer's tongue weight is extremely light. Too light of a ball mount tongue and hitch causes a dangerous condition called trailer sway. When the tongue weight is extremely heavy, the steering of the towing vehicle is affected.

The typical ski boat weighs about 3,500 pounds plus trailer weight of 1,000 pounds, speed boats weigh around 8,000 pounds with trailer weight of 1,300 pounds, and cabin cruisers weigh about 8,700 pounds add another 1,600 pounds of trailer weight totaling 10,300 for the cabin cruiser on its trailer. Example, the cabin cruiser tongue weight is between 1,030 to 1,545 pounds. Example, a 22 feet camper trailer weighs 3,600 pounds with tongue weight between 360 to 540 pounds is hauling in tandem a cabin cruiser boat and trailer triple tow by a truck. Clearly the weight of the last trailer of cabin cruiser boat and trailer is going to cause trailer sway.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of the embodiment showing the tandem trailer dolly apparatus. This apparatus primary use is hitched to the rear of the trailer being towed by the vehicle where tandem trailer weight is supported on the dolly. The ball hitch adjusts up and down for horizontal leveling of tandem trailer. A shock-absorbing system to cushion from bumps.

FIG. 2 is a top view of the embodiment showing the tandem trailer dolly apparatus has two tongue hitches. The ball hitch is coaxial with the axle and at the midway point of the trailer. A steel plate supports the weight of the adjustable ball hitch.

FIG. 3 is a side view of the embodiment showing the tandem trailer dolly apparatus connect by tongue and hitch method to the adjoining tandem trailers rear and the last trailer attaches by means of ball hitch centered on top of trailer dolly apparatus, said tongue weight from last trailer causes a downward force through the dolly center to the ground.

FIG. 4 is a top view of the embodiment showing the tandem trailer dolly apparatus has no turning capabilities fixing the hitch attachments to the rear of adjoining trailer with up and down swivel functions. The last trailer tongue and ball hitch of the triple towing tandem trailers can swivel side to side and up and down.

FIG. 5 is a side view of the embodiments ball hitch mechanism with adjustable height in sleeve and fastener pin. That adjustable ball hitch centers coaxial with the axle and at the midway point, measured midpoint from right side to left side intersecting coaxial line with midway ling of the trailer.

FIG. 6 is a side and top view of the embodiments pintle hook towing receiver that has an adjustable trailer hitch. The adjustable trailer hitch has holes for pinning through towing receiver cylindrical holes. The pins have a locking mechanism. The adjustable trailer hitch is welded or bolted into the dolly frame.

FIG. 7 is a side view of the embodiments tandem trailer dolly apparatus with no shock-absorbing system. The axle is attached to the dolly frame by welding or- bolting. Hubs for wheels attach to the axle. Fenders are provided to stop wheel projectiles. The ball hitch is adjustable up and down. The tongue towing receivers adjust up and down through the adjustable trailer hitches for horizontal leveling of dolly. Two pins have locking ends through the towing receivers and adjustable trailer hitches.

FIG. 8 is a top view of the embodiments tandem trailer dolly apparatus has a steel plate platform welded or bolted to the dolly frame. The adjustable ball hitch is attached to this platform. The tongue towing receivers adjustable trailer hitches framing mounts attach to the platform welded or bolted.

FIG. 9 is a bottom view of the embodiments tandem trailer dolly apparatus. Showing axle mounted to the frame with no suspension for absorbing bumps. The adjustable ball hitch sleeve is coaxial with the axle and at the midpoint center of the axle. The tongue towing receivers adjustable trailer hitches framing mounts attach to the platform welded or bolted.

DETAILED DESCRIPTION OF THE INVENTION

The materials in manufacturing the tandem trailer dolly apparatus are steel, rubber tires, grease for the hubs, and wheels. The fastening means will be welding, clipping, pinning, capping, and bolting the materials together, or all five attaching ways combined.

As seen in FIG. 1, a tandem trailer dolly embodiment 23 comprises an axial 1 for wheels 2, leaf spring suspension 3 with bracket 10 and U-bolt 9 with nuts to hold the leaf springs in place is provided to cushion the shock of potholes and bridges etc. A frame 4 made of steel. A ball hitch 5 to hitch the tongue of a tandem trailer has a trailer hitch sleeve for adjustable hitch slides up and down. The ball mount 6 is screw or weld the ball hitch 5 on adjustable hitch. The adjustable hitch has cylindrical holes for height adjustment and is static when pinned. The adjustable hitch is for horizontal leveling of tail end tandem trailer. The trailer hitch tongues 7, latches 11, and pins 12 are provided to secure the dolly 23 with no side to side turning ability only swivel up and down. Fenders 8 are provided to protect from projectiles striking tandem trailer.

FIG. 2 discloses the embodiment 23, which has a steel plate 13 for structural stability of trailer dolly 23 frame 4 and fastens the ball hitch 5 in place. A view of the dual tongue hitches 7 and latches 11 are provided. The fenders 8 are seen.

FIG. 3 discloses embodiment 23, tandem trailer dolly 23 being towed by trailer 14 is towed tandem with trailer 17, showing trailer 17 tongue 16 latch 12 swivels side to side on ball 5, ball hitch mount 6 and hitch 7. All of embodiment 23, primary trailer 14, and tandem trailer dolly 23 assisting secondary trailer 17 are in triple tandem towing, towing vehicle not seen in diagram. Adjustable ball hitch sleeve 6 is for horizontal leveling.

FIG. 4 discloses embodiment 23, that has no pivotal side to side abilities at tongue hitches 7 only up and down motion that is attached to trailer hitches 15 at the rear of trailer 14. That tandem trailer 17 is attached through ball hitch to tongue hitch 7 of trailer 17 can pivot side to side or up and down.

FIG. 5 discloses embodiment 24, with ball 5 and hitch 18 is adjustable with cylindrical holes 22 for pinning 20. A hitch sleeve 19 welded to plate 13 provide the framework to hold ball 5 hitch 18 in place under towing conditions.

FIG. 6 discloses embodiment 25, shows towing receiver 31 with steel square formed 29 for pinning 28, towing receiver is all one piece 31 and 29. There are two pins 28 with locks 27 for pinning 28 and locking 27 towing receiver 31 to adjustable trailer hitch 30 through holes 22. The adjustable trailer hitch 30 is framed 4 into tandem trailer dolly 25.

FIG. 7 discloses embodiment 26, that shows this tandem trailer dolly 26 has adjustable trailer hitch 30 and towing receiver 31 to line up primary trailer horizontal level. The ball hitch 5 attached by ball mount 6 is either screwed or welded to adjustable hitch 18. The adjustable ball 5 and hitch 18 are for horizontal leveling of rear tandem trailer. There is additional framing 4 to dolly 26 frame 4 securing adjustable hitch 30 that holds towing receiver 31 by means of pins 28 with locks 27. The towing receiver 31 and adjustable hitch 30 is for horizontal leveling of tandem trailer dolly 26. The axle 1 is attached directly to frame 4 by welding or U-bolts. The wheels 2 have fenders 34 to stop projectiles when wheels 2 contact lose debris on the road.

FIG. 8 discloses embodiment 26, showing steel plate 32 is welded or bolted to frame 4. Here is clearly seen tow hitch sleeve 19, adjustable hitch 18, and ball hitch 5. The adjustable ball 5 hitch 18 make horizontal leveling easy for rear tandem trailer. The adjustable hitches 30 fastening pins 28 and locks 27, secure towing receivers 31 bases 29 to adjustable hitches 30. The adjustable towing receiver's 31 capability allow the tandem trailer dolly 26 to be horizontally leveled. The pintle hook towing receivers 31 are stationary allowing no side to side turning, the only rotation is up and down.

FIG. 9 discloses embodiment 26, which shows how axle 33 is mounted to dolly frame 4 by means of welding or U-bolting. This axle 33 is square and at the axle 33 midpoint is hitch sleeve 19. This functioning hitch sleeve 19 passing through axle 33, has hitch sleeve 19 and axle 33 welded as one unit. By having hitch sleeve 19 welded to axle 33 attached by welding or U-bolts to steel plate 32. This way hitch sleeve 19 slides adjustable ball hitch 18 ball 5 down to the steel plate 32 platform or other heights up in an attempt' to horizontal level towed rear tandem trailer.

While the invention has been described in connection with what is presently the most considered practical and preferred embodiment(s). It is to be understood that the invention is not limited to the disclosed embodiment(s) but, on the contrary is intended to cover various modifications and equivalent arrangements included within the scope of the appended claims. 

What is claimed:
 1. This invention relates to trailer dollies and more particularly to a tandem trailer dolly in-combination with triple towing of vehicle a primary trailer and a secondary tandem trailer. The tandem trailer dolly has dual tongue hitches for connecting to the rear end of the primary trailer and will not pivot in turning. The tandem trailer dolly is the means of attaching the secondary trailer tongue hitch that pivots in turning from towing vehicle, said dolly supports the weight not the rear end hitches of the primary trailer. No additional forces from the secondary trailer affects the towing vehicle or primary trailer due to the downward force. The force is supported by the dolly frame, axle, and wheels. Tandem trailer dolly apparatus comprises: two wheels for engaging the ground and an axle mounted with hubs carried by wheels; the two wheels, hubs, and axle attach to said dolly frame; a ball hitch housing adjustable for horizontal leveling of secondary trailer are attached to said dolly frame; said dolly frame supports ball hitch sleeve for pinning and locking of adjustable ball hitch; a hitching mechanism with adjustable height is mounted coaxial to the axle and midpoint of the axle that is designed to pivot the secondary trailer in tandem; tongue hitches extending from said dolly frame for attachment to the towed or primary trailer's rear end for tandem towing; tongue hitching mechanisms have adjustable trailer hitches attached to frame for horizontal leveling of said trailer dolly; a shock absorbing mechanism is provided between said axle mount and said frame housing, whereby said shock absorbing mechanism absorbs potholes etc. of dolly frame; fenders are provided to keep projectiles from hitting towed or secondary trailer; the dolly apparatus can be detached from one towing trailer and attached to another as may be desired, which is in support of no additional weight to the rear end of any primary trailer, so that primary trailer tongue hitched has no additional forced affect to the towing vehicle.
 2. The tandem trailer dolly of claim 1 wherein said shock-absorbing system comprises leaf springs between said axle and mounted to said frame.
 3. The tandem trailer dolly of claim 1 wherein no shock-absorbing system is provided to the frame.
 4. The tandem trailer dolly of claim 1 comprising an adjustable ball hitch extends upward and descends downward trough said dolly frame is provided for secondary trailer tongue hitch that pivots horizontally level.
 5. The tandem trailer dolly of claim 1 comprises more than one hitch mechanisms that fix the dolly from pivot turning during towing. The only pivots are up and down.
 6. The tandem trailer dolly of claim 1 comprises more than one hitch mechanisms that fix the dolly from pivot turning during towing. Said hitching mechanisms are adjustable for horizontal leveling of said dolly. The only pivots are up and down.
 7. The tandem trailer dolly of claim 1 comprising an attached axle with no shock-absorbing mechanism.
 8. The tandem trailer dolly of claim 1 comprising hitching mechanisms other than ball and hitch.
 9. The tandem trailer dolly of claim 1 comprises a single tongue hitch allowing pivot turning of said dolly.
 10. A tandem trailer dolly in-combination with triple towing of vehicle a primary trailer and a secondary tandem trailer. The tandem trailer dolly has dual tongue hitches for connecting to the rear end of the primary trailer and will not pivot in turning. The tandem trailer dolly has the means of attaching the secondary trailer tongue hitch mechanism that allows pivot in turning while in towing from the vehicle and supports the weight not the rear end hitches of the primary trailer. No additional forces from the secondary trailer affect the towing vehicle or primary trailer due to the downward force is supported by said dolly frame, suspensions, dual axles, and multiple wheels. Tandem trailer dolly apparatus comprises:
 11. The tandem trailer dolly of claim 10 wherein duel axles and duel leaf springs are provided.
 12. The tandem trailer dolly of claim 10 has dual wheels.
 13. The tandem trailer dolly of claim 10 wherein said shock-absorbing mechanism is between said axle mount and said frame.
 14. The tandem trailer dolly of claim 10 wherein the shock-absorbing system comprises leaf springs cushion axles that are mounted to said frame.
 15. The tandem trailer dolly of claim 10 comprises a single tongue hitch allowing pivot turning of said dolly.
 16. The tandem trailer dolly of claim 10 comprising a hitch mechanism elevated from said dolly frame wherein said hitch provides secondary trailer hitch the connection that can pivot.
 17. The tandem trailer dolly of claim 10 comprises an adjustable ball hitch extends upward and descends downward trough said dolly frame is provided for secondary trailer tongue hitch that pivots horizontally level.
 18. The tandem trailer dolly of claim 10 comprises an adjustable ball hitch extends upward and descends downward trough said dolly frames center. Said dolly frame midway points are measured from front to rear of frame midway point and left side to right side midway point. The intersection of these two midway points is where the adjustable hitch centers.
 19. The tandem trailer dolly of claim 10 comprises more than one hitch mechanisms that fix the dolly from pivot turning during towing. Said hitching mechanisms is adjustable for horizontal leveling of said dolly. The only pivots are up and down.
 20. The tandem trailer dolly of claim 10 comprising hitching mechanisms other than ball and hitch.
 21. The tandem trailer dolly of claim 10 comprises no adjustable features at said dolly dual hitches.
 22. The tandem trailer dolly of claim 10 wherein duel axles and duel leaf springs are provided.
 23. The tandem trailer dolly of claim 10 has multiple wheels.
 24. The tandem trailer dolly wherein the hitches have chains to attach to the primary trailers rear.
 25. The tandem trailer dolly wherein when the vehicle moves forward, chains are attached to the rear of primary trailer for alignment of said dolly hitches when towing vehicle moves forward.
 26. The tandem trailer dolly wherein the ball hitch and adjustable sleeve mechanism is not limited as shown. There are a plethora hitching mechanisms to attach trailers for towing.
 27. The tandem trailer dolly wherein no adjusting hitches are necessary.
 28. The tandem trailer dolly wherein half axle shafts are mounted the frame. 